MODFLOW-6 groundwater flow model and model scenarios of the Ogallala and Arikaree aquifers, Rosebud Sioux Tribe national areas, South Dakota

The Ogallala and Arikaree aquifers are important water resources for the Rosebud Sioux Tribe and are used extensively for irrigation and domestic water supplies. Drought or increased withdrawals from the Ogallala and Arikaree aquifers in the Rosebud Sioux Tribal lands potentially affect water levels in these aquifers. MODFLOW-6 (version 6.6.0) groundwater flow models of the Ogallala and Arikaree aquifers were constructed to update the models from Long and Putnam (2010) created using MODFLOW-2000 (version 1.7). The purpose of the MODFLOW-6 models was to provide numerical model files and structures more easily modified than previous versions for multiple drought scenarios. Models included in the MODFLOW-6 updates are a transient model that is the basic simulation model used by Long and Putnam (2010), a base forecast model, and scenarios with outputs of water levels and water budgets.